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Sat, 05 Sep 2026 06:25:18 -0700 (PDT) Received: from rock-5b-plus ([61.83.209.48]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cc465376831sm903641a12.9.2026.09.05.06.25.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Sep 2026 06:25:17 -0700 (PDT) Date: Sat, 5 Sep 2026 22:25:02 +0900 From: Sidong Yang To: Igor Paunovic Cc: Tomeu Vizoso , Oded Gabbay , Heiko Stuebner , Jiaxing Hu , dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] accel/rocket: search every core slot when a core is removed Message-ID: References: <20260904125936.26234-1-royalnet026@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260904125936.26234-1-royalnet026@gmail.com> On Fri, Sep 04, 2026 at 02:59:36PM +0200, Igor Paunovic wrote: > rocket_remove() decrements rdev->num_cores for each core it removes, > while find_core_for_dev() searches slots 0 to num_cores - 1. Unbinding > the cores in the order they were bound therefore loses the last one: by > the time it is removed the search range has already shrunk past its > slot, so find_core_for_dev() returns -1 and rocket_remove() gives up > without doing anything. > > num_cores never reaches zero, rocket_device_fini() never runs, and the > file-scoped rdev keeps pointing at a device that is going away. Binding > the cores again starts from that stale count, because rocket_probe() > takes rdev->num_cores as the slot to fill. On an RK3588, which describes > three cores, the second round lands on slots 1, 2 and 3 while rdev->cores > was allocated with room for three: > > rocket fdab0000.npu: Rockchip NPU core 1 version: 1179210309 > rocket fdac0000.npu: Rockchip NPU core 2 version: 1179210309 > rocket fdad0000.npu: Rockchip NPU core 3 version: 1179210309 > > The write to rdev->cores[3] is past the end of the array. > > Nothing in tree reads the core array often enough to notice, so the > overrun is silent today. It turned up while testing a devfreq series on > top of this, where a worker walks every core a few times a second, and > UBSAN caught the first bool it read out of the overrun entry: > > UBSAN: invalid-load in drivers/accel/rocket/rocket_devfreq.c:47:10 > load of value 5 is not a valid value for type '_Bool' > Workqueue: devfreq_wq devfreq_monitor > > Record how many slots were allocated and search all of them. Every core > is then found on removal, num_cores reaches zero, the device is torn down > and a later bind starts from a clean rdev. > > This does not make unbinding a single core out of several work. probe > still takes num_cores as the slot to fill, so rebinding one core while > its siblings stay bound would write over a slot that is already in use, > and rocket_open() still reaches for cores[0] whether or not anything is > there. Both of those want more thought than a fix should carry. > > Found by unbinding and rebinding all three cores on an Orange Pi 5 Plus. > With this applied, 25 unbind/rebind rounds and 5 module unload/reload > rounds run clean there: the cores land in slots 0, 1 and 2 every time, > whichever order they are bound in, and the shared supply goes back to a > single user after each round. > > Fixes: ed98261b4168 ("accel/rocket: Add a new driver for Rockchip's NPU") > Cc: stable@vger.kernel.org > Signed-off-by: Igor Paunovic > Assisted-by: LLM sparse checkpatch > --- > drivers/accel/rocket/rocket_device.c | 2 ++ > drivers/accel/rocket/rocket_device.h | 1 + > drivers/accel/rocket/rocket_drv.c | 2 +- > 3 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/accel/rocket/rocket_device.c b/drivers/accel/rocket/rocket_device.c > index 46e6ee1e72c5f..efd004194c1af 100644 > --- a/drivers/accel/rocket/rocket_device.c > +++ b/drivers/accel/rocket/rocket_device.c > @@ -31,6 +31,8 @@ struct rocket_device *rocket_device_init(struct platform_device *pdev, > if (of_device_is_available(core_node)) > num_cores++; > > + rdev->max_cores = num_cores; > + > rdev->cores = devm_kcalloc(dev, num_cores, sizeof(*rdev->cores), GFP_KERNEL); > if (!rdev->cores) > return ERR_PTR(-ENOMEM); > diff --git a/drivers/accel/rocket/rocket_device.h b/drivers/accel/rocket/rocket_device.h > index ce662abc01d3d..c62d567010696 100644 > --- a/drivers/accel/rocket/rocket_device.h > +++ b/drivers/accel/rocket/rocket_device.h > @@ -19,6 +19,7 @@ struct rocket_device { > > struct rocket_core *cores; > unsigned int num_cores; > + unsigned int max_cores; Hi Igor, I've tested this patch in Radxa Rock 5 B+ and it works. The test is that unbinding all cores in sequence 0,1,2 and rebind all. It seems that there is other issue about num_core. For example, sched_to_core() finds core for sched with num_core and it could make same error like find_core_for_dev(). Tested-by: Sidong Yang # RK3588, 3 cores Thanks, Sidong > }; > > struct rocket_device *rocket_device_init(struct platform_device *pdev, > diff --git a/drivers/accel/rocket/rocket_drv.c b/drivers/accel/rocket/rocket_drv.c > index 8bbbce594883e..2bcfe4ab3c68f 100644 > --- a/drivers/accel/rocket/rocket_drv.c > +++ b/drivers/accel/rocket/rocket_drv.c > @@ -223,7 +223,7 @@ static int find_core_for_dev(struct device *dev) > { > struct rocket_device *rdev = dev_get_drvdata(dev); > > - for (unsigned int core = 0; core < rdev->num_cores; core++) { > + for (unsigned int core = 0; core < rdev->max_cores; core++) { > if (dev == rdev->cores[core].dev) > return core; > } > -- > 2.43.0 >